You're absolutely right, a silenced gunshot would have shown up on the cockpit voice recorder. Maybe that's why we have not been allowed to listen to them? Of course, I'm sure you realize, none of the contents of any of the CVRs have been released to the public. We are told that all the black boxes from the two WTC planes were not recovered-- despite accounts from several firefighters who say they found the boxes and turned them over to the FBI.

The only CVR that anyone from the public has been able to listen to is the one from UAL93, played for a private audience of victims' families. Even some of them suspected the CVR had been tampered with. This was the CVR that somehow captured conversation among the heroes discussing how to break open the cockpit door, despite the fact that a CVR can only record what goes on inside the cockpit.

Your story is disintegrating. Before I explain, let me briefly point out that we discussed the "missing" black boxes here, and the reports that they were found are simply a lie; and that a Cockpit Voice Recorder, commonly referred to as a CVR, is fairly sensitive and indeed quite capable of picking up yells and other conversation outside the cockpit door, particularly when hundreds of people are willing to replay every scrap over and over and over again until they figure out what's on tape.

Let me also say that I do appreciate that you, A-Train, have actually provided us some details on what you think happened. Very few Troothers ever do this, most are content to complain about anomalies without attempting any explanation at all. You still haven't brought much in the way of evidence, but perhaps we'll work on that next.

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Now, then, let me explain what's going on with your theory. There's a fine line in the Scientific Method, one that you have crossed. I refer to the fine line between refining a hypothesis and making excuses.

Virtually all hypotheses can use refinement, whether it's in the form of added details, more explicit explanations, moving assumptions from merely "credible" to "supported by evidence," and sharpening numbers. This is true of the so-called Official Theory of Sept. 11th as well -- starting from the rough hypothesis of "19 terrorists hijacked four airliners and crashed them into three buildings," it has since been refined in terms of who the terrorists were, how the planes were hijacked, what preparations led up to the event, why safeguards failed, and precisely how buildings performed after being hit.

Refining hypotheses is a necessary part of science, and should always be done when new or conflicting facts are discovered. Sometimes, we cannot add precise refinements, but must instead make assumptions. This is a subjective process, hence the fine line. So how do we evaluate our assumptions?

Some measures are simple -- an assumption that violates all known physical laws is a poor one, for instance. Others, such as "Occam's Razor" or the observation that simpler assumptions are in general preferred, are difficult to evaluate on their own. The simplest hypothesis is not always the correct one.

But, in this case, we don't have to evaluate assumptions on their own, because we have multiple hypotheses, all being tested against the same body of facts. An assumption that strengthens one hypothesis against those facts is a good one. An assumption that evades the known facts, or depends on new facts that are not readily available, is not. This is just a way of preventing a factual test from applying to the hypothesis.

The latter case is an "excuse." Excuses are bad assumptions because the only purpose they serve is to keep viable an otherwise untenable hypothesis. If there are no valid hypotheses currently in the running, then speculation is warranted, but if there are, we should simply accept that the other hypotheses are better. We can still continue to look for new facts, of course, and we need not completely abandon our own pet hypothesis, but we cannot use these excuses without acknowledging that they are a serious flaw.

As an example, consider two hypotheses, what I will call the Official Theory (OT) and the A-Train Theory (ATT), held up to new facts. (This isn't really a new fact, but let's treat it as one to examine the process.)

New Fact: A small fraction of phone calls made from the hijacked aircraft suggest that firearms may have been on board.

OT: We need to add the assumption that the reports may have been mistaken, as is often the case, similar to mistaken reports of bombs on the planes. Alternately, we need to consider that firearms may have been present, in which case there is an additional security failure that needs investigating.

ATT: We need to add the fact that guns were taken on board the aircraft. This means there was an additional security failure that needs investigating.

So far, so good, right? Ah, but these assumptions have consequences.

Consequence: There is no record of gunfire on the recovered Cockpit Voice Recorders.

OT: Per our theory, there should have been no need for gunfire on board the aircraft. Guns, if present, could have merely been an additional deterrent used to aid the hijackers in taking control of the aircraft.

ATT: The guns must have had silencers.

Aha. There's our first excuse. There's no evidence for silencers at all, this is pure speculation -- and it's speculation that needs to be true in order for the competing theory to remain credible. Let's continue:

Consequence: Even with a silencer, gunfire would probably have been audible on the Cockpit Voice Recorder.

OT: As before, there is no need for gunfire, silenced or otherwise. This fact does not challenge our hypothesis.

ATT: In that case, the CVR records must have been suppressed or altered.

There's the second excuse, and it's a big one. In order for that to be true, you need to believe that many people consciously altered a CVR record, interfering in a supremely important investigation -- and many, many more people let it happen, failed to report inconsistencies, or were simply duped.

This is not impossible in the strict sense of the word, but it's hardly likely, and nobody should accept this assumption without some pretty hard evidence behind it. Already we see a "snowball effect" as the excuses get bigger and bigger, and the Conspiracy Theory grows along with it.

Thus, my Inflationary Model of Conspiracy Theories, stated thus:

"A Good Theory can be distinguished from a Conspiracy Theory as follows: When repeatedly exposed to scrutiny, the Conspiracy Theory requires more and more people involved, and more and more extraordinary events in order to prevent self-contradiction. A Good Theory, in contrast, remains approximately static in complexity as it is refined."

This is the same principle that makes little kids such rotten liars. Whenever they fib, they don't have enough experience to make things consistent, so they throw out any old thing that pops into their head. Upon questioning it doesn't match, the lies get bigger, and so on.

Back to A-Train, if you can figure out how to explain your theory without bringing the whole FBI, FAA, NTSB, and the nation of Israel into it, then please do. But if you can't, then I'm afraid your hypothesis isn't worth a thing.